为间隔生成大数字

Question

我需要随机产生两个数字L和R，使得1≤L≤R≤10^ 18。 怎么做到这一点？请帮忙。

我的代码：

#define MAXN 1000
int main(){
    srand(time(NULL));
    int x=rand()%MAXN;
    int y=rand()%100000;
    int z=rand()%100000;
    long L =x; 
    long R=x*y*z;
    assert(L<=R && L>=1 && L<=1000000000000000000 && R>=1 && R<=1000000000000000000); 
    cout<<L<<" "<<R<<"\n";
}

显然它不正确。所以我正在寻找最好的方法。

方法2：

        const long min = 1;
        const long max = 1000000000000000000;

        std::default_random_engine generator(rd());
        std::uniform_int_distribution<long> distribution(min,max);
        long L = distribution(generator);

        const long min1 = L;
        const long max1 = 1000000000000000000;
        std::default_random_engine generator1(rd());
        std::uniform_int_distribution<long> distribution1(min1,max1);
        long  R = distribution1(generator1);
        assert(L<=R && L>=1 && L<=1000000000000000000 && R>=1 && R<=1000000000000000000); 
        cout<<L<<" "<<R<<"\n";